Seperate piece top and bottom, make sure overlaps are downwind.
Apply with low heat and pull wrinkles out as much as you can before shrinking. Do not shrink until the edges are fully sealed down, and don't use too Much heat to shrink, experiment with the temp before you fully commit.
Leave a couple of inches spare at the tips then stretch the covering round using enough heat too let it stretch.
Get plenty of scalpel blades to trim, it takes the edge off really quickly.
Finally, use Profilm, it's well worth the extra cost